The present invention relates to a method and apparatus for automatically shutting in a producing well whenever the pressure in the well annulus is lost and more particularly relates to a method and apparatus for shutting in a producing well whenever the casing in the well is ruptured or accidentally penetrated by a second well being drilled in the proximity of the producing well.
In developing certain oil fields, directional drilling techniques are used to drill several wells from a relatively centralized surface location. Where the wells are significantly spaced at the surface, intersection of two wells occurs only rarely. However, where the wells are drilled in "clusters", e.g. at many offshore locations and at some landbased locations, intersection of one or more wells during drilling is a stark reality. In cluster drilling, anywhere from twelve to twenty wells may be started within a surface spacing of from five to eight feet of one from another. Each well is designed to be drilled vertically downward to a desired depth before it is "kicked off" into a deviated path toward its final destination. It can easily be seen that if a well varies slightly during the initial vertical drilling stage, there is a real probability that it will penetrate the vertical portion of a closely spaced, adjacent well.
Traditionally, all wells in a cluster were first drilled before any of the wells were put on production. However, recently due to technical developments, e.g. larger offshore platforms and the increased demand for petroleum, some wells in a cluster may now be drilled, completed, and put on production before all of the wells in the cluster are drilled. If the wellbore of a well being drilled intersects a live producing well, there is a real danger that the well being drilled may "blow out" and/or a fire or other hazardous condition may occur at either the producing well and/or the well being drilled. Therefore, the need is obvious for quickly and safely shutting in a producing well, if and when the producing wellbore is accidentally penetrated by a well being drilled.